1. Technical Field
The present invention relates to a semiconductor apparatus having a magnetic shielding film and to a method for manufacturing the semiconductor apparatus.
2. Related Art
In the trends of miniaturization and improved performances of electronic devices in recent years, enhancements in the response speed of semiconductor apparatus such as large scale integrated circuit (LSI) incorporated in these electronic devices are required. In order to meet such requirements, operating frequency of the semiconductor apparatus is increased, resulting in an increased frequency of signal that is propagated through interconnects of the semiconductor apparatus. This causes generation of electromagnetic radiation noises, thereby causing a problem of inducing electromagnetic interferences to other electronic devices. On the contrary, miniaturizations in the electric wiring configurations of the semiconductor apparatus causes considerable noise generated between adjacent interconnects (interconnect crosstalk), causing a problem of inducing malfunctions of the semiconductor apparatus. Therefore, in order to ensure higher reliability of semiconductor apparatus, it is desirable to reduce electromagnetic radiation noise so long as I am possible.
An approach of utilizing magnetic loss of magnetic material is well known as a procedure for reducing electromagnetic radiation noise. For example, Japanese Patent Application Publication No. H06 (1994)-21060 discloses a semiconductor device having a multiple-layered interconnect structure including a ferrimagnetic material film. In the multiple-layered interconnect structure, an interconnect layer, an interlayer insulating film, a ferrimagnetic material film, an interlayer insulating film and an interconnect layer are formed on the semiconductor substrate in this sequence. The ferrimagnetic material film is disposed between one interconnect layer and the other interconnect layer to exhibit an electromagnetic shield function. On the other hand, Japanese Patent Application Publication No. H09 (1997)-330929 discloses a semiconductor device having a layer of a magnetic material formed on an insulating layer including a metallic interconnect layer. Japanese Patent Application Publication No. H06 (1994)-120027 discloses a structure including a FeCo ferromagnetic thin film having positive magnetostriction and an intermediate layer composed of an RFeCo alloy thin film having negative magnetostriction or a spinel ferrite magnetic thin film deposited thereon. The deposited structure allows reducing effective magnetostriction in the whole film.
However, when a semiconductor device includes a film of a magnetic material, a metallic material of this film of the magnetic material may be diffused, considerably deteriorating electrical characteristics of the semiconductor device. The reason for the deterioration is considered that the diffusion of the materials composing the magnetic film is promoted during the manufacturing processes for the semiconductor device, reaching to the interconnect layer to cause a contamination with a metal. For example, in the multiple-layered interconnect structure disclosed in Japanese Patent Application Publication No. H06-21060, the material from the ferrimagnetic material film may be diffused through the interlayer insulating film during manufacturing process to cause a fear for creating contamination with metal.